Okay... I have been going through this forum for a week trying to figure out what I am doing wrong. I have a Nuvi 255W, just recently updated with Garmin Express. I originally downloaded a torrent map but obviously did not work. I have downloaded the 'Garmin city Navigator North America NT 2015.30 Unlocked IMG' file and unzipped it. I have followed the instructions down to the letter. The device only has about 1.8GB of free space and I am using a 8GB SD card. I also tried adding a unl file. Still no luck. I also tried the Garmin Unlocker but its not wanting to run properly. The GPS still boots properly, and connects to the computer, there's no issues there. When I reboot the GPS it says "No detailed maps found that support routing. The Nuvi cannot be used without them."
Any ideas please! I am very frustrated at this point.